Verify That the Equation Is an Identity $$\csc ( s + t ) = \frac { \operatorname { cscs } \csc t } { \cot t + \cot s }$$

Verify that the equation is an identity.
- $$\csc ( s + t ) = \frac { \operatorname { cscs } \csc t } { \cot t + \cot s }$$